drivers/isdn/gigaset/ser-gigaset.c

   1 /* This is the serial hardware link layer (HLL) for the Gigaset 307x isdn
   2  * DECT base (aka Sinus 45 isdn) using the RS232 DECT data module M101,
   3  * written as a line discipline.
   4  *
   5  * =====================================================================
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation; either version 2 of
   9  * the License, or (at your option) any later version.
  10  * =====================================================================
  11  */
  12
  13 #include "gigaset.h"
  14
  15 #include <linux/module.h>
  16 #include <linux/moduleparam.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/tty.h>
  19 #include <linux/completion.h>
  20
  21 /* Version Information */
  22 #define DRIVER_AUTHOR "Tilman Schmidt"
  23 #define DRIVER_DESC "Serial Driver for Gigaset 307x using Siemens M101"
  24
  25 #define GIGASET_MINORS     1
  26 #define GIGASET_MINOR      0
  27 #define GIGASET_MODULENAME "ser_gigaset"
  28 #define GIGASET_DEVNAME    "ttyGS"
  29
  30 /* length limit according to Siemens 3070usb-protokoll.doc ch. 2.1 */
  31 #define IF_WRITEBUF 264
  32
  33 MODULE_AUTHOR(DRIVER_AUTHOR);
  34 MODULE_DESCRIPTION(DRIVER_DESC);
  35 MODULE_LICENSE("GPL");
  36 MODULE_ALIAS_LDISC(N_GIGASET_M101);
  37
  38 static int startmode = SM_ISDN;
  39 module_param(startmode, int, S_IRUGO);
  40 MODULE_PARM_DESC(startmode, "initial operation mode");
  41 static int cidmode = 1;
  42 module_param(cidmode, int, S_IRUGO);
  43 MODULE_PARM_DESC(cidmode, "stay in CID mode when idle");
  44
  45 static struct gigaset_driver *driver;
  46
  47 struct ser_cardstate {
  48         struct platform_device  dev;
  49         struct tty_struct       *tty;
  50         atomic_t                refcnt;
  51         struct completion       dead_cmp;
  52 };
  53
  54 static struct platform_driver device_driver = {
  55         .driver = {
  56                 .name = GIGASET_MODULENAME,
  57         },
  58 };
  59
  60 static void flush_send_queue(struct cardstate *);
  61
  62 /* transmit data from current open skb
  63  * result: number of bytes sent or error code < 0
  64  */
  65 static int write_modem(struct cardstate *cs)
  66 {
  67         struct tty_struct *tty = cs->hw.ser->tty;
  68         struct bc_state *bcs = &cs->bcs[0];     /* only one channel */
  69         struct sk_buff *skb = bcs->tx_skb;
  70         int sent = -EOPNOTSUPP;
  71
  72         if (!tty || !tty->driver || !skb)
  73                 return -EINVAL;
  74
  75         if (!skb->len) {
  76                 dev_kfree_skb_any(skb);
  77                 bcs->tx_skb = NULL;
  78                 return -EINVAL;
  79         }
  80
  81         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
  82         if (tty->ops->write)
  83                 sent = tty->ops->write(tty, skb->data, skb->len);
  84         gig_dbg(DEBUG_OUTPUT, "write_modem: sent %d", sent);
  85         if (sent < 0) {
  86                 /* error */
  87                 flush_send_queue(cs);
  88                 return sent;
  89         }
  90         skb_pull(skb, sent);
  91         if (!skb->len) {
  92                 /* skb sent completely */
  93                 gigaset_skb_sent(bcs, skb);
  94
  95                 gig_dbg(DEBUG_INTR, "kfree skb (Adr: %lx)!",
  96                         (unsigned long) skb);
  97                 dev_kfree_skb_any(skb);
  98                 bcs->tx_skb = NULL;
  99         }
 100         return sent;
 101 }
 102
 103 /*
 104  * transmit first queued command buffer
 105  * result: number of bytes sent or error code < 0
 106  */
 107 static int send_cb(struct cardstate *cs)
 108 {
 109         struct tty_struct *tty = cs->hw.ser->tty;
 110         struct cmdbuf_t *cb, *tcb;
 111         unsigned long flags;
 112         int sent = 0;
 113
 114         if (!tty || !tty->driver)
 115                 return -EFAULT;
 116
 117         cb = cs->cmdbuf;
 118         if (!cb)
 119                 return 0;       /* nothing to do */
 120
 121         if (cb->len) {
 122                 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 123                 sent = tty->ops->write(tty, cb->buf + cb->offset, cb->len);
 124                 if (sent < 0) {
 125                         /* error */
 126                         gig_dbg(DEBUG_OUTPUT, "send_cb: write error %d", sent);
 127                         flush_send_queue(cs);
 128                         return sent;
 129                 }
 130                 cb->offset += sent;
 131                 cb->len -= sent;
 132                 gig_dbg(DEBUG_OUTPUT, "send_cb: sent %d, left %u, queued %u",
 133                         sent, cb->len, cs->cmdbytes);
 134         }
 135
 136         while (cb && !cb->len) {
 137                 spin_lock_irqsave(&cs->cmdlock, flags);
 138                 cs->cmdbytes -= cs->curlen;
 139                 tcb = cb;
 140                 cs->cmdbuf = cb = cb->next;
 141                 if (cb) {
 142                         cb->prev = NULL;
 143                         cs->curlen = cb->len;
 144                 } else {
 145                         cs->lastcmdbuf = NULL;
 146                         cs->curlen = 0;
 147                 }
 148                 spin_unlock_irqrestore(&cs->cmdlock, flags);
 149
 150                 if (tcb->wake_tasklet)
 151                         tasklet_schedule(tcb->wake_tasklet);
 152                 kfree(tcb);
 153         }
 154         return sent;
 155 }
 156
 157 /*
 158  * send queue tasklet
 159  * If there is already a skb opened, put data to the transfer buffer
 160  * by calling "write_modem".
 161  * Otherwise take a new skb out of the queue.
 162  */
 163 static void gigaset_modem_fill(unsigned long data)
 164 {
 165         struct cardstate *cs = (struct cardstate *) data;
 166         struct bc_state *bcs;
 167         int sent = 0;
 168
 169         if (!cs || !(bcs = cs->bcs)) {
 170                 gig_dbg(DEBUG_OUTPUT, "%s: no cardstate", __func__);
 171                 return;
 172         }
 173         if (!bcs->tx_skb) {
 174                 /* no skb is being sent; send command if any */
 175                 sent = send_cb(cs);
 176                 gig_dbg(DEBUG_OUTPUT, "%s: send_cb -> %d", __func__, sent);
 177                 if (sent)
 178                         /* something sent or error */
 179                         return;
 180
 181                 /* no command to send; get skb */
 182                 if (!(bcs->tx_skb = skb_dequeue(&bcs->squeue)))
 183                         /* no skb either, nothing to do */
 184                         return;
 185
 186                 gig_dbg(DEBUG_INTR, "Dequeued skb (Adr: %lx)",
 187                         (unsigned long) bcs->tx_skb);
 188         }
 189
 190         /* send skb */
 191         gig_dbg(DEBUG_OUTPUT, "%s: tx_skb", __func__);
 192         if (write_modem(cs) < 0)
 193                 gig_dbg(DEBUG_OUTPUT, "%s: write_modem failed", __func__);
 194 }
 195
 196 /*
 197  * throw away all data queued for sending
 198  */
 199 static void flush_send_queue(struct cardstate *cs)
 200 {
 201         struct sk_buff *skb;
 202         struct cmdbuf_t *cb;
 203         unsigned long flags;
 204
 205         /* command queue */
 206         spin_lock_irqsave(&cs->cmdlock, flags);
 207         while ((cb = cs->cmdbuf) != NULL) {
 208                 cs->cmdbuf = cb->next;
 209                 if (cb->wake_tasklet)
 210                         tasklet_schedule(cb->wake_tasklet);
 211                 kfree(cb);
 212         }
 213         cs->cmdbuf = cs->lastcmdbuf = NULL;
 214         cs->cmdbytes = cs->curlen = 0;
 215         spin_unlock_irqrestore(&cs->cmdlock, flags);
 216
 217         /* data queue */
 218         if (cs->bcs->tx_skb)
 219                 dev_kfree_skb_any(cs->bcs->tx_skb);
 220         while ((skb = skb_dequeue(&cs->bcs->squeue)) != NULL)
 221                 dev_kfree_skb_any(skb);
 222 }
 223
 224
 225 /* Gigaset Driver Interface */
 226 /* ======================== */
 227
 228 /*
 229  * queue an AT command string for transmission to the Gigaset device
 230  * parameters:
 231  *      cs              controller state structure
 232  *      buf             buffer containing the string to send
 233  *      len             number of characters to send
 234  *      wake_tasklet    tasklet to run when transmission is complete, or NULL
 235  * return value:
 236  *      number of bytes queued, or error code < 0
 237  */
 238 static int gigaset_write_cmd(struct cardstate *cs, const unsigned char *buf,
 239                              int len, struct tasklet_struct *wake_tasklet)
 240 {
 241         struct cmdbuf_t *cb;
 242         unsigned long flags;
 243
 244         gigaset_dbg_buffer(cs->mstate != MS_LOCKED ?
 245                              DEBUG_TRANSCMD : DEBUG_LOCKCMD,
 246                            "CMD Transmit", len, buf);
 247
 248         if (len <= 0)
 249                 return 0;
 250
 251         if (!(cb = kmalloc(sizeof(struct cmdbuf_t) + len, GFP_ATOMIC))) {
 252                 dev_err(cs->dev, "%s: out of memory!\n", __func__);
 253                 return -ENOMEM;
 254         }
 255
 256         memcpy(cb->buf, buf, len);
 257         cb->len = len;
 258         cb->offset = 0;
 259         cb->next = NULL;
 260         cb->wake_tasklet = wake_tasklet;
 261
 262         spin_lock_irqsave(&cs->cmdlock, flags);
 263         cb->prev = cs->lastcmdbuf;
 264         if (cs->lastcmdbuf)
 265                 cs->lastcmdbuf->next = cb;
 266         else {
 267                 cs->cmdbuf = cb;
 268                 cs->curlen = len;
 269         }
 270         cs->cmdbytes += len;
 271         cs->lastcmdbuf = cb;
 272         spin_unlock_irqrestore(&cs->cmdlock, flags);
 273
 274         spin_lock_irqsave(&cs->lock, flags);
 275         if (cs->connected)
 276                 tasklet_schedule(&cs->write_tasklet);
 277         spin_unlock_irqrestore(&cs->lock, flags);
 278         return len;
 279 }
 280
 281 /*
 282  * tty_driver.write_room interface routine
 283  * return number of characters the driver will accept to be written
 284  * parameter:
 285  *      controller state structure
 286  * return value:
 287  *      number of characters
 288  */
 289 static int gigaset_write_room(struct cardstate *cs)
 290 {
 291         unsigned bytes;
 292
 293         bytes = cs->cmdbytes;
 294         return bytes < IF_WRITEBUF ? IF_WRITEBUF - bytes : 0;
 295 }
 296
 297 /*
 298  * tty_driver.chars_in_buffer interface routine
 299  * return number of characters waiting to be sent
 300  * parameter:
 301  *      controller state structure
 302  * return value:
 303  *      number of characters
 304  */
 305 static int gigaset_chars_in_buffer(struct cardstate *cs)
 306 {
 307         return cs->cmdbytes;
 308 }
 309
 310 /*
 311  * implementation of ioctl(GIGASET_BRKCHARS)
 312  * parameter:
 313  *      controller state structure
 314  * return value:
 315  *      -EINVAL (unimplemented function)
 316  */
 317 static int gigaset_brkchars(struct cardstate *cs, const unsigned char buf[6])
 318 {
 319         /* not implemented */
 320         return -EINVAL;
 321 }
 322
 323 /*
 324  * Open B channel
 325  * Called by "do_action" in ev-layer.c
 326  */
 327 static int gigaset_init_bchannel(struct bc_state *bcs)
 328 {
 329         /* nothing to do for M10x */
 330         gigaset_bchannel_up(bcs);
 331         return 0;
 332 }
 333
 334 /*
 335  * Close B channel
 336  * Called by "do_action" in ev-layer.c
 337  */
 338 static int gigaset_close_bchannel(struct bc_state *bcs)
 339 {
 340         /* nothing to do for M10x */
 341         gigaset_bchannel_down(bcs);
 342         return 0;
 343 }
 344
 345 /*
 346  * Set up B channel structure
 347  * This is called by "gigaset_initcs" in common.c
 348  */
 349 static int gigaset_initbcshw(struct bc_state *bcs)
 350 {
 351         /* unused */
 352         bcs->hw.ser = NULL;
 353         return 1;
 354 }
 355
 356 /*
 357  * Free B channel structure
 358  * Called by "gigaset_freebcs" in common.c
 359  */
 360 static int gigaset_freebcshw(struct bc_state *bcs)
 361 {
 362         /* unused */
 363         return 1;
 364 }
 365
 366 /*
 367  * Reinitialize B channel structure
 368  * This is called by "bcs_reinit" in common.c
 369  */
 370 static void gigaset_reinitbcshw(struct bc_state *bcs)
 371 {
 372         /* nothing to do for M10x */
 373 }
 374
 375 /*
 376  * Free hardware specific device data
 377  * This will be called by "gigaset_freecs" in common.c
 378  */
 379 static void gigaset_freecshw(struct cardstate *cs)
 380 {
 381         tasklet_kill(&cs->write_tasklet);
 382         if (!cs->hw.ser)
 383                 return;
 384         dev_set_drvdata(&cs->hw.ser->dev.dev, NULL);
 385         platform_device_unregister(&cs->hw.ser->dev);
 386         kfree(cs->hw.ser);
 387         cs->hw.ser = NULL;
 388 }
 389
 390 static void gigaset_device_release(struct device *dev)
 391 {
 392         struct platform_device *pdev =
 393                 container_of(dev, struct platform_device, dev);
 394
 395         /* adapted from platform_device_release() in drivers/base/platform.c */
 396         //FIXME is this actually necessary?
 397         kfree(dev->platform_data);
 398         kfree(pdev->resource);
 399 }
 400
 401 /*
 402  * Set up hardware specific device data
 403  * This is called by "gigaset_initcs" in common.c
 404  */
 405 static int gigaset_initcshw(struct cardstate *cs)
 406 {
 407         int rc;
 408
 409         if (!(cs->hw.ser = kzalloc(sizeof(struct ser_cardstate), GFP_KERNEL))) {
 410                 pr_err("out of memory\n");
 411                 return 0;
 412         }
 413
 414         cs->hw.ser->dev.name = GIGASET_MODULENAME;
 415         cs->hw.ser->dev.id = cs->minor_index;
 416         cs->hw.ser->dev.dev.release = gigaset_device_release;
 417         if ((rc = platform_device_register(&cs->hw.ser->dev)) != 0) {
 418                 pr_err("error %d registering platform device\n", rc);
 419                 kfree(cs->hw.ser);
 420                 cs->hw.ser = NULL;
 421                 return 0;
 422         }
 423         dev_set_drvdata(&cs->hw.ser->dev.dev, cs);
 424
 425         tasklet_init(&cs->write_tasklet,
 426                      &gigaset_modem_fill, (unsigned long) cs);
 427         return 1;
 428 }
 429
 430 /*
 431  * set modem control lines
 432  * Parameters:
 433  *      card state structure
 434  *      modem control line state ([TIOCM_DTR]|[TIOCM_RTS])
 435  * Called by "gigaset_start" and "gigaset_enterconfigmode" in common.c
 436  * and by "if_lock" and "if_termios" in interface.c
 437  */
 438 static int gigaset_set_modem_ctrl(struct cardstate *cs, unsigned old_state, unsigned new_state)
 439 {
 440         struct tty_struct *tty = cs->hw.ser->tty;
 441         unsigned int set, clear;
 442
 443         if (!tty || !tty->driver || !tty->ops->tiocmset)
 444                 return -EINVAL;
 445         set = new_state & ~old_state;
 446         clear = old_state & ~new_state;
 447         if (!set && !clear)
 448                 return 0;
 449         gig_dbg(DEBUG_IF, "tiocmset set %x clear %x", set, clear);
 450         return tty->ops->tiocmset(tty, NULL, set, clear);
 451 }
 452
 453 static int gigaset_baud_rate(struct cardstate *cs, unsigned cflag)
 454 {
 455         return -EINVAL;
 456 }
 457
 458 static int gigaset_set_line_ctrl(struct cardstate *cs, unsigned cflag)
 459 {
 460         return -EINVAL;
 461 }
 462
 463 static const struct gigaset_ops ops = {
 464         gigaset_write_cmd,
 465         gigaset_write_room,
 466         gigaset_chars_in_buffer,
 467         gigaset_brkchars,
 468         gigaset_init_bchannel,
 469         gigaset_close_bchannel,
 470         gigaset_initbcshw,
 471         gigaset_freebcshw,
 472         gigaset_reinitbcshw,
 473         gigaset_initcshw,
 474         gigaset_freecshw,
 475         gigaset_set_modem_ctrl,
 476         gigaset_baud_rate,
 477         gigaset_set_line_ctrl,
 478         gigaset_m10x_send_skb,  /* asyncdata.c */
 479         gigaset_m10x_input,     /* asyncdata.c */
 480 };
 481
 482
 483 /* Line Discipline Interface */
 484 /* ========================= */
 485
 486 /* helper functions for cardstate refcounting */
 487 static struct cardstate *cs_get(struct tty_struct *tty)
 488 {
 489         struct cardstate *cs = tty->disc_data;
 490
 491         if (!cs || !cs->hw.ser) {
 492                 gig_dbg(DEBUG_ANY, "%s: no cardstate", __func__);
 493                 return NULL;
 494         }
 495         atomic_inc(&cs->hw.ser->refcnt);
 496         return cs;
 497 }
 498
 499 static void cs_put(struct cardstate *cs)
 500 {
 501         if (atomic_dec_and_test(&cs->hw.ser->refcnt))
 502                 complete(&cs->hw.ser->dead_cmp);
 503 }
 504
 505 /*
 506  * Called by the tty driver when the line discipline is pushed onto the tty.
 507  * Called in process context.
 508  */
 509 static int
 510 gigaset_tty_open(struct tty_struct *tty)
 511 {
 512         struct cardstate *cs;
 513
 514         gig_dbg(DEBUG_INIT, "Starting HLL for Gigaset M101");
 515
 516         pr_info(DRIVER_DESC "\n");
 517
 518         if (!driver) {
 519                 pr_err("%s: no driver structure\n", __func__);
 520                 return -ENODEV;
 521         }
 522
 523         /* allocate memory for our device state and intialize it */
 524         if (!(cs = gigaset_initcs(driver, 1, 1, 0, cidmode,
 525                                   GIGASET_MODULENAME)))
 526                 goto error;
 527
 528         cs->dev = &cs->hw.ser->dev.dev;
 529         cs->hw.ser->tty = tty;
 530         atomic_set(&cs->hw.ser->refcnt, 1);
 531         init_completion(&cs->hw.ser->dead_cmp);
 532
 533         tty->disc_data = cs;
 534
 535         /* OK.. Initialization of the datastructures and the HW is done.. Now
 536          * startup system and notify the LL that we are ready to run
 537          */
 538         if (startmode == SM_LOCKED)
 539                 cs->mstate = MS_LOCKED;
 540         if (!gigaset_start(cs)) {
 541                 tasklet_kill(&cs->write_tasklet);
 542                 goto error;
 543         }
 544
 545         gig_dbg(DEBUG_INIT, "Startup of HLL done");
 546         return 0;
 547
 548 error:
 549         gig_dbg(DEBUG_INIT, "Startup of HLL failed");
 550         tty->disc_data = NULL;
 551         gigaset_freecs(cs);
 552         return -ENODEV;
 553 }
 554
 555 /*
 556  * Called by the tty driver when the line discipline is removed.
 557  * Called from process context.
 558  */
 559 static void
 560 gigaset_tty_close(struct tty_struct *tty)
 561 {
 562         struct cardstate *cs = tty->disc_data;
 563
 564         gig_dbg(DEBUG_INIT, "Stopping HLL for Gigaset M101");
 565
 566         if (!cs) {
 567                 gig_dbg(DEBUG_INIT, "%s: no cardstate", __func__);
 568                 return;
 569         }
 570
 571         /* prevent other callers from entering ldisc methods */
 572         tty->disc_data = NULL;
 573
 574         if (!cs->hw.ser)
 575                 pr_err("%s: no hw cardstate\n", __func__);
 576         else {
 577                 /* wait for running methods to finish */
 578                 if (!atomic_dec_and_test(&cs->hw.ser->refcnt))
 579                         wait_for_completion(&cs->hw.ser->dead_cmp);
 580         }
 581
 582         /* stop operations */
 583         gigaset_stop(cs);
 584         tasklet_kill(&cs->write_tasklet);
 585         flush_send_queue(cs);
 586         cs->dev = NULL;
 587         gigaset_freecs(cs);
 588
 589         gig_dbg(DEBUG_INIT, "Shutdown of HLL done");
 590 }
 591
 592 /*
 593  * Called by the tty driver when the tty line is hung up.
 594  * Wait for I/O to driver to complete and unregister ISDN device.
 595  * This is already done by the close routine, so just call that.
 596  * Called from process context.
 597  */
 598 static int gigaset_tty_hangup(struct tty_struct *tty)
 599 {
 600         gigaset_tty_close(tty);
 601         return 0;
 602 }
 603
 604 /*
 605  * Read on the tty.
 606  * Unused, received data goes only to the Gigaset driver.
 607  */
 608 static ssize_t
 609 gigaset_tty_read(struct tty_struct *tty, struct file *file,
 610                  unsigned char __user *buf, size_t count)
 611 {
 612         return -EAGAIN;
 613 }
 614
 615 /*
 616  * Write on the tty.
 617  * Unused, transmit data comes only from the Gigaset driver.
 618  */
 619 static ssize_t
 620 gigaset_tty_write(struct tty_struct *tty, struct file *file,
 621                   const unsigned char *buf, size_t count)
 622 {
 623         return -EAGAIN;
 624 }
 625
 626 /*
 627  * Ioctl on the tty.
 628  * Called in process context only.
 629  * May be re-entered by multiple ioctl calling threads.
 630  */
 631 static int
 632 gigaset_tty_ioctl(struct tty_struct *tty, struct file *file,
 633                   unsigned int cmd, unsigned long arg)
 634 {
 635         struct cardstate *cs = cs_get(tty);
 636         int rc, val;
 637         int __user *p = (int __user *)arg;
 638
 639         if (!cs)
 640                 return -ENXIO;
 641
 642         switch (cmd) {
 643
 644         case FIONREAD:
 645                 /* unused, always return zero */
 646                 val = 0;
 647                 rc = put_user(val, p);
 648                 break;
 649
 650         case TCFLSH:
 651                 /* flush our buffers and the serial port's buffer */
 652                 switch (arg) {
 653                 case TCIFLUSH:
 654                         /* no own input buffer to flush */
 655                         break;
 656                 case TCIOFLUSH:
 657                 case TCOFLUSH:
 658                         flush_send_queue(cs);
 659                         break;
 660                 }
 661                 /* Pass through */
 662
 663         default:
 664                 /* pass through to underlying serial device */
 665                 rc = n_tty_ioctl_helper(tty, file, cmd, arg);
 666                 break;
 667         }
 668         cs_put(cs);
 669         return rc;
 670 }
 671
 672 /*
 673  * Called by the tty driver when a block of data has been received.
 674  * Will not be re-entered while running but other ldisc functions
 675  * may be called in parallel.
 676  * Can be called from hard interrupt level as well as soft interrupt
 677  * level or mainline.
 678  * Parameters:
 679  *      tty     tty structure
 680  *      buf     buffer containing received characters
 681  *      cflags  buffer containing error flags for received characters (ignored)
 682  *      count   number of received characters
 683  */
 684 static void
 685 gigaset_tty_receive(struct tty_struct *tty, const unsigned char *buf,
 686                     char *cflags, int count)
 687 {
 688         struct cardstate *cs = cs_get(tty);
 689         unsigned tail, head, n;
 690         struct inbuf_t *inbuf;
 691
 692         if (!cs)
 693                 return;
 694         if (!(inbuf = cs->inbuf)) {
 695                 dev_err(cs->dev, "%s: no inbuf\n", __func__);
 696                 cs_put(cs);
 697                 return;
 698         }
 699
 700         tail = inbuf->tail;
 701         head = inbuf->head;
 702         gig_dbg(DEBUG_INTR, "buffer state: %u -> %u, receive %u bytes",
 703                 head, tail, count);
 704
 705         if (head <= tail) {
 706                 /* possible buffer wraparound */
 707                 n = min_t(unsigned, count, RBUFSIZE - tail);
 708                 memcpy(inbuf->data + tail, buf, n);
 709                 tail = (tail + n) % RBUFSIZE;
 710                 buf += n;
 711                 count -= n;
 712         }
 713
 714         if (count > 0) {
 715                 /* tail < head and some data left */
 716                 n = head - tail - 1;
 717                 if (count > n) {
 718                         dev_err(cs->dev,
 719                                 "inbuf overflow, discarding %d bytes\n",
 720                                 count - n);
 721                         count = n;
 722                 }
 723                 memcpy(inbuf->data + tail, buf, count);
 724                 tail += count;
 725         }
 726
 727         gig_dbg(DEBUG_INTR, "setting tail to %u", tail);
 728         inbuf->tail = tail;
 729
 730         /* Everything was received .. Push data into handler */
 731         gig_dbg(DEBUG_INTR, "%s-->BH", __func__);
 732         gigaset_schedule_event(cs);
 733         cs_put(cs);
 734 }
 735
 736 /*
 737  * Called by the tty driver when there's room for more data to send.
 738  */
 739 static void
 740 gigaset_tty_wakeup(struct tty_struct *tty)
 741 {
 742         struct cardstate *cs = cs_get(tty);
 743
 744         clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 745         if (!cs)
 746                 return;
 747         tasklet_schedule(&cs->write_tasklet);
 748         cs_put(cs);
 749 }
 750
 751 static struct tty_ldisc_ops gigaset_ldisc = {
 752         .owner          = THIS_MODULE,
 753         .magic          = TTY_LDISC_MAGIC,
 754         .name           = "ser_gigaset",
 755         .open           = gigaset_tty_open,
 756         .close          = gigaset_tty_close,
 757         .hangup         = gigaset_tty_hangup,
 758         .read           = gigaset_tty_read,
 759         .write          = gigaset_tty_write,
 760         .ioctl          = gigaset_tty_ioctl,
 761         .receive_buf    = gigaset_tty_receive,
 762         .write_wakeup   = gigaset_tty_wakeup,
 763 };
 764
 765
 766 /* Initialization / Shutdown */
 767 /* ========================= */
 768
 769 static int __init ser_gigaset_init(void)
 770 {
 771         int rc;
 772
 773         gig_dbg(DEBUG_INIT, "%s", __func__);
 774         if ((rc = platform_driver_register(&device_driver)) != 0) {
 775                 pr_err("error %d registering platform driver\n", rc);
 776                 return rc;
 777         }
 778
 779         /* allocate memory for our driver state and intialize it */
 780         if (!(driver = gigaset_initdriver(GIGASET_MINOR, GIGASET_MINORS,
 781                                           GIGASET_MODULENAME, GIGASET_DEVNAME,
 782                                           &ops, THIS_MODULE)))
 783                 goto error;
 784
 785         if ((rc = tty_register_ldisc(N_GIGASET_M101, &gigaset_ldisc)) != 0) {
 786                 pr_err("error %d registering line discipline\n", rc);
 787                 goto error;
 788         }
 789
 790         return 0;
 791
 792 error:
 793         if (driver) {
 794                 gigaset_freedriver(driver);
 795                 driver = NULL;
 796         }
 797         platform_driver_unregister(&device_driver);
 798         return rc;
 799 }
 800
 801 static void __exit ser_gigaset_exit(void)
 802 {
 803         int rc;
 804
 805         gig_dbg(DEBUG_INIT, "%s", __func__);
 806
 807         if (driver) {
 808                 gigaset_freedriver(driver);
 809                 driver = NULL;
 810         }
 811
 812         if ((rc = tty_unregister_ldisc(N_GIGASET_M101)) != 0)
 813                 pr_err("error %d unregistering line discipline\n", rc);
 814
 815         platform_driver_unregister(&device_driver);
 816 }
 817
 818 module_init(ser_gigaset_init);
 819 module_exit(ser_gigaset_exit);